The present invention generally relates to dielectric fluids used in metallized polypropylene film AC capacitors.
The failures of metallized polymeric film capacitors in AC applications is due primarily to partial discharges or corona and excessive clearing. To eliminate corona the dielectric fluid should possess excellent gas absorptivity, produce low swellability when in contact with polypropylene film, possess oxygen in order to prevent carbonization during clearing, and should not penetrate the capacitor roll. These favorable properties were found in cycloaliphatic epoxides as impregnant for metallized polypropylene film capacitors.